US 3665238 A
Description (OCR text may contain errors)
United States Patent Van Esdonk et al.
ELECTRIC GAS DISCHARGE TUBE HAVING VACUUM TIGHT SEALING MEANS FOR A PLURALITY OF SUPPLY LEADS POSITIONED CLOSE TOGETHER Inventors: Johannes Van Esdonk; Joannes Franciscus Marla Janssen, both of Emmasingel, Eindhoven, Netherlands Assignee: U. S. Philips Corporation, New York, NY.
Filed: June 11, 1970 Appl. No.: 45,438
Foreign Application Priority Data June 13, 1969 Netherlands ..69091 19 [1.8. CI. ..313/220, 313/267, 313/268, 313/269, 315/169 TV Int. Cl. ..H0lj 17/16 FieldofSearch ..3l5/l69 R, 169 TV, 337; 313/258, 268, 269, 210, 220, 109.5, 267
 3,665,238 [451 May23,1972
Primary Examiner-Roy Lake Assistant Examiner-Palmer C. Demeo Attamey--Frank R. Trifari ABSTRACT A gas discharge tube having intersecting conductors which are loosely situated in grooves of an insulating plate having open sides remote from the base of the tube. The insulating plate is kept urged against a window plate by a spring. The electrodes are connected to lead-in conductors placed close together in the base plate of the tube. The lead-in conductors pass through ceramic tubes inserted in the base plate of the tube and are vacuum sealed by means of a vitreous insulating material.
5 Claims, 5 Drawing Figures ELECTRIC GAS DISCHARGE TUBE HAVING VACUUM TIGHT SEALING MEANS FOR A PLURALITY OF SUPPLY LEADS POSITIONED CLOSE TOGETHER The invention relates to an electric gas discharge tube having an electrode system consisting of a number of rod-shaped electrodes which are connected to lead-in conductors provided in a base-plate and which are arranged in grooves in an insulating plate, the grooves being open on one side. The invention relates in particular to a gas discharge tube in which the electrode system consists of two or more sets of parallel conductors arranged in groups, the conductors of the various groups intersecting each other at an angle as is described in the prior British Pat. application Nr. 25,715/68.
The French Pat. specification No. 1,485,958 describes a gas discharge tube in which the rod-shaped electrodes placed in opengrooves of the tube bottom are bent and themselves change into a lead-in member. Each conductor is passed through the base plate in a vacuum-tight manner. When using a large number of rod-shaped electrodes which are situated parallel to and at a small distance from each other, as is described in the above-mentioned prior patent application, difficulties are experienced when the electrodes are separately secured in the wall of the tube in a vacuum-tight manner, since the lead-in places are located close together so that the possibility of air leaks exists if the electrodes are sealed in the wall of the tube without further measures, in particular if the rods have such a thickness that they can also serve as contact pins.
If, however, each electrode placed in open grooves is connected at one end to a flexible, thin wire, which wires are sealed in the wall of the tube or are connected to lead-in members, the danger exists that the rod-shaped electrodes can jump out of the grooves in the case of a shock or impact, unless special measures are taken to fix the electrodes in the grooves, which usually is cumbersome.
A very favorable and reliable arrangement is obtained in a gas discharge tube having an electrode system consisting of a number of rod-shaped electrodes which are connected to lead-in conductors provided in a base plate and which are placed in grooves of an insulating plate which are open on one side, if, according to the invention, the grooves are provided in one or more separate supporting plates consisting at least superficially of an insulating material, each rod-shaped electrode being connected, by means of a flexible connection conductor', to a lead-in conductor provided in the base plate, the supporting plate being urged, by means of spring action, against a transparent window provided in the wall of the envelope opposite to the .base plate with the open sides of the grooves remote from the base plate. The electrodes consist of parallel rods which are subdivided into two or more groups in which the electrodes of various groups intersect each other at an angle. Two groups of electrodes can be provided on the same side of the supporting plate in grooves having different depths, but the groups may alternatively each be provided on one side of the supporting plate. The grooves facing the base plate are covered by a plate provided between the base plate and the supporting plate. This plate need not be transparent and may therefore consist, besides of glass, also of a ceramic plate or an electrolytically oxidized metal plate. The supporting plate must then be perforated at the intersections of the electrodes, in which perforations the discharges can occur. The lead-in conductors provided in the base plate are preferably placed at such a small distance from each other in one or several rows that their distance is equal to the distance between the rod-shaped electrodes connected to the lead-in conductors.
The base plate and the cover plate with the window preferably consist of metal, such as femico, the window being secured, by means of a suitable cement, in an aperture of a metal plate having an upright edge and flange which is connected to the base plate in a vacuum-tight manner. The lead-in conductors are arranged close together in ceramic tubes which are provided in apertures of the base plate and are all together connected to the base plate in a vacuum-tight manner by means of a vitreous insulating substance.
In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a cross-sectional view and FIG. 2 is a plan view, partly in cross-section, of a given embodiment of a gas discharge tube according to the invention, and
FIG. 3 is a cross-sectional view of a number of lead-in conductors, while FIG. 4 is a cross-sectional view and FIG. 5 is a plan view, partly in cross-section of another embodiment of a tube according to the invention.
Reference numeral 1 in FIG. 1 denotes a metal base plate consisting, for example, of femico. A metal plate 2 having an upright edge 3 and a flange 4 of the same material constitutes, with the base plate 1, a vacuum vessel in which a gas atmosphere, for example, consisting of argon, is provided.
The plate 2 comprises a transparent window 5, for example, consisting of a glass plate, which is secured in a conventional manner in a rabbet of the metal plate 2 by means of a suitable cement.
An independent supporting plate consisting at least superfiv cially of an insulating material is present in the space inside the envelope 1, 2 and is provided with deep grooves having rod-shaped electrodes 7 and shallow grooves at right angles to the first-mentioned grooves and having rod-shaped electrodes 8. The supporting plate 6 may consist of aluminum which is superficially oxidized electrolytically as is described in the above-mentioned prior application. The deep grooves can then be squeezed a little at the ends so as to fix the rods 7. However, this fixing may alternatively be done by means of cement.
The electrodes 7 and 8 are connected, by means of connection wires 9, to lead-in conductors 10 placed in corresponding rows. The conductors 10 are provided in the base plate 1 at the same distance from each other between the center lines as the distance between the center lines of the parallel electrodes 7 and 8, respectively, connected thereto. This is found possible by the construction shown in FIG. 3. In the embodiment shown in FIG. 3, in which the conductors 10 are passed through thin-walled ceramic tubes placed in the perforations, the distance between the center lines of the perforations may .be smaller than 2 mm. The vacuum-tight connection of the conductors l0 and the tubes 11 to the base plate 1 is obtained by providing a vitreous cement 12, for example, readily melting ceramic material or a type of glass having a coefficient of expansion which is adapted to that of the base plate 1, over the ceramic tubes 1 l and around the supply conductor 10.
It has proved possible with this construction to use a distance between the center lines of 1.4 mm for the lead-in conductors. As a result of this the distance between the center lines of the lead-in conductors may be equal to that of the rodshaped electrodes. The conductors themselves may have a diameter of 0.65 mm. The tubes 11 which consist, for example, of aluminum oxide have a wall thickness of 0.3 mm. When using the conventional pressure-sealing, it is substantially not possible to make the distance between the center lines of the perforations smaller than 2.5 mm, while the thickness of the lead-in conductors may then be at most 0.5 mm. The lead-in conductors would then have to be placed in a zig-zag manner in several rows.
The connection wires 9 are connected to the associated lead-in conductors 10, after which the upper plate 2 with the flange 4 is provided on the base plate 1 andthe edge of the flange 4 is welded to the base plate 1 in a vacuum-tight manner in a current of argon. The connection, however, may alternatively be carried out by means of a suitable solder.
In order to support the insulating supporting plate 6 with the electrodes 7, 8 in the envelope in an immovable manner, a spring 13 is provided which urges the supporting plate 6 against the window 5 with the open sides of the grooves in which the electrodes 7 and 8 are situated remote from the base plate 1. As a result of this it is also prevented that the electrodes 8 can jump out of the grooves by a shock or impact.
The end of the electrodes remote from the connection conductors 9 actually is entirely free, while the flexible connection conductors 9 are not capable of sufficiently fixing the electrodes. So in this embodiment the electrodes 7 need only be fixed in the grooves which is possible, for example, by providing a small quantity of cement in the ends of the grooves.
In the embodiment shown in FIGS. 4 and 5 the separate fixing of the electrodes in the grooves has become entirely superfluous. The grooves for the electrodes 7 are present in the side of the supporting plate 16 facing the base plate 1. These grooves are covered by an insulating plate 14 which is urged against the supporting plate 16 by means of the action of the spring 13, while simultaneously the supporting plate is urged against the window 5. The insulating plate 14 need not be transparent and may therefore in addition to glass be a ceramic material or electrolytically oxidized aluminum.
The plate 16 comprises a large number of perforations, namely a perforation at each intersection of the grooves for the electrodes 7 and 8, in which perforations a discharge can occur.
In this embodiment the spring 13 can be laid on the base plate 1, after which successively the electrodes are laid in the grooves of the inverted plate 16 directed upwards, covered with the plate 14, after which the assembly is turned over and laid on the spring 13. The electrodes 8 are then laid in the open grooves of the supporting plate 16 directed upwards, the connection conductors 9 are connected to the lead-in conductors 10 and the cover 2 with the window 5 is placed on the grooves of the electrodes 8. The edge of the flange 4 is then welded to the base plate 1, the envelope is evacuated and provided with a suitable gas filling. For that purpose an exhaust tube (not shown) can be provided in a conventional manner, for example, in the base plate.
Two or more lead-in conductors may serve for heating and possible evaporating a getter.
It is also possible to provide several supporting plates one on the other so as to provide groups of electrodes in two or more planes. The electrodes of each group are then preferably connected to an associated row of lead-in members.
The tubes according to the invention may be used for the display of television pictures. At each intersection of the electrodes 7 and 8 a gas discharge may occur which becomes visible as a light dot if between the electrodes which intersect each other at this point a suitable voltage difference is set up.
Although two particular embodiments have been described, the invention may alternatively be used with difierently shaped tubes.
What is claimed is:
l. A gas discharge tube comprising a metal base plate, a window plate cooperating with said base plate to form a discharge space, and an electrode system comprising an insu- 10 jacent lead-in conductors is substantially equal to the distance between the centerlines of adjacent electrodes, a vitreous material for forming a vacuum tight connection between said lead-in conductors and said ceramic tubes, a plurality of flexible members for connecting each lead-in conductor to an electrode, and resilient means positioned between confronting surfaces of said base and insulating plates for urging said insulating plate against said window plate.
2. A gas discharge tube as claimed in claim 1 wherein said plurality of juxtaposed rod-shaped electrodes comprises at least two sets of electrodes, the electrodes of each set intersecting each other at an angle.
3. gas discharge tube as claimed in claim 1 wherein the distance between the centerlines of the lead-in conductors is 1.4 mm. and the diameter of the lead-in conductor is 0.6 mm.
4. A gas discharge tube as claimed in claim 1 wherein the reentrant surface portion of said insulating plate forms at least two groups of open-ended grooves intersecting each other at an angle, each group having a different groove depth.
5. A gas discharge tube comprising a metal base plate, a window plate cooperating with said base plate to form a discharge space and an electrode system comprising a plurality of insulating plates within said discharge space, each of said insulating plates having a reentrant surface portion remote from said base plate wherein the reentrant surface portion forms at least two groups of open-ended grooves intersecting each other at an angle, a plurality of groups of juxtaposed rodshaped electrodes within said grooves, each of said electrodes in the same group lying in the same plane positioned at one depth within said grooves and each of said electrodes in the other group lying in the same plane positioned at a second depth within said grooves, a plurality of ceramic tubes extending through said base plate into said discharge space, a plurality of lead-in conductors within said ceramic tubes arranged so that the distance between centerlines of adjacent lead-in conductors is substantially equal to the distance between the centerlines of adjacent electrodes lying in the same plane, a vitreous material for forming a vacuum-tight connection between said lead-in conductors and said ceramic tubes, a plurality of flexible members for connecting each lead-in conductor to an electrode, and resilient means for urging said insulating plates against each other and said window plate.